CHEAPest way to convert rear axle bolt pattern to big bolt pattern???

i welded and redrilled my sb 83/4 axles you just have to be careful on the orientation cuz when you weld them the flange gets really hard from the heat. i used carbide drills . they have been on my dart for 3 years now with no problems and im running a crate 360 420hp magnum with a 4 speed and 410s